In recent years, in accordance with a larger scale, finer wiring, an increase in amount of power source wiring, and a lower voltage of an integrated circuit such as an LSI (Large Scale Integration), a power source network analysis is becoming very important at a design stage of the integrated circuit.
The power source network analysis deems network-like power source wiring from a power source to a load element in the integrated circuit as a single electric resistor and analyzes whether a sufficient voltage can be applied to the load element under the influence of a voltage drop due to this electric resistor (hereinafter referred to as an IR drop; The IR drop means the voltage drop according to Ohm's law; “I” represents current and “R” represents resistance).
The power source network analysis uses much memory of a computer at the time of execution of the analysis. Enormousness of analysis execution time causes a lack of computer resources and increases the number of problems not to be analyzed and the number of man-hours required for detection and analysis of a problematic power source network and correction of problematic power source error spots. Therefore, conventionally, various techniques were devised for accurately and efficiently performing the power source network analysis (see Japanese Patent Application Laid-open No. 2003-233637 and Japanese Patent Application Laid-open No. 2007-52591).
However, the above conventional technologies have had the following problems. Namely, a further larger scale and enhanced degree of integration of the circuit are significant in the integrated circuit in recent years. The integrated circuit of the larger scale and with the enhanced degree of integration has wiring for connecting respective load elements inside made finer and more complicated. The integrated circuit has come to be designed to achieve the lower voltage to restrain power consumption. Under such circumstances, it is becoming difficult for the above conventional technologies to perform the power source network analysis of the integrated circuit accurately and efficiently.